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AUSCERT External Security Bulletin Redistribution
ESB-2021.3875
Advisory (icsa-21-315-01) WECON PLC Editor
12 November 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: WECON PLC Editor
Publisher: ICS-CERT
Operating System: Network Appliance
Impact/Access: Execute Arbitrary Code/Commands -- Existing Account
Resolution: None
CVE Names: CVE-2021-42707 CVE-2021-42705
Original Bulletin:
https://us-cert.cisa.gov/ics/advisories/icsa-21-315-01
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ICS Advisory (ICSA-21-315-01)
WECON PLC Editor
Original release date: November 11, 2021
Legal Notice
All information products included in https://us-cert.cisa.gov/ics are provided
"as is" for informational purposes only. The Department of Homeland Security
(DHS) does not provide any warranties of any kind regarding any information
contained within. DHS does not endorse any commercial product or service,
referenced in this product or otherwise. Further dissemination of this product
is governed by the Traffic Light Protocol (TLP) marking in the header. For more
information about TLP, see https://us-cert.cisa.gov/tlp/ .
1. EXECUTIVE SUMMARY
o CVSS v3 7.8
o ATTENTION: Low attack complexity
o Vendor: WECON
o Equipment: PLC Editor
o Vulnerabilities: Stack-based Buffer Overflow, Out-of-bounds Write
2. RISK EVALUATION
Successful exploitation of these vulnerabilities may allow arbitrary code
execution.
3. TECHNICAL DETAILS
3.1 AFFECTED PRODUCTS
The following versions of PLC Editor ladder logic software are affected:
o PLC Editor: Versions 1.3.8 and prior
3.2 VULNERABILITY OVERVIEW
3.2.1 STACK-BASED BUFFER OVERFLOW CWE-121
The affected product is vulnerable to a stack-based buffer overflow while
processing project files, which may allow an attacker to execute arbitrary
code.
CVE-2021-42705 has been assigned to this vulnerability. A CVSS v3 base score of
7.8 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:N/UI:R/S:U/
C:H/I:H/A:H ).
3.2.2 OUT-OF-BOUNDS WRITE CWE-787
The affected product is vulnerable to an out-of-bounds write while processing
project files, which may allow an attacker to execute arbitrary code.
CVE-2021-42707 has been assigned to this vulnerability. A CVSS v3 base score of
7.8 has been calculated; the CVSS vector string is ( AV:L/AC:L/PR:N/UI:R/S:U/
C:H/I:H/A:H ).
3.3 BACKGROUND
o CRITICAL INFRASTRUCTURE SECTORS: Critical Manufacturing, Energy, Water and
Wastewater Systems
o COUNTRIES/AREAS DEPLOYED: Worldwide
o COMPANY HEADQUARTERS LOCATION: China
3.4 RESEARCHER
Natnael Samson (@NattiSamson), working with Trend Micro's Zero Day Initiative,
reported these vulnerabilities to CISA.
4. MITIGATIONS
WECON has not responded to requests to work with CISA to mitigate these
vulnerabilities. Users of these affected products are invited to contact WECON
technical support for additional information.
CISA also recommends users take the following measures to protect themselves
from social engineering attacks:
o Do not click web links or open unsolicited attachments in email messages.
o Refer to Recognizing and Avoiding Email Scams for more information on
avoiding email scams.
o Refer to Avoiding Social Engineering and Phishing Attacks for more
information on social engineering attacks.
CISA reminds organizations to perform proper impact analysis and risk
assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices
on the ICS webpage on us-cert.cisa.gov . Several recommended practices are
available for reading and download, including Improving Industrial Control
Systems Cybersecurity with Defense-in-Depth Strategies .
Additional mitigation guidance and recommended practices are publicly available
on the ICS webpage on us-cert.cisa.gov in the Technical Information Paper,
ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation
Strategies .
Organizations observing any suspected malicious activity should follow their
established internal procedures and report their findings to CISA for tracking
and correlation against other incidents.
No known public exploits specifically target these vulnerabilities. These
vulnerabilities are not exploitable remotely.
For any questions related to this report, please contact the CISA at:
Email: CISAservicedesk@cisa.dhs.gov
Toll Free: 1-888-282-0870
CISA continuously strives to improve its products and services. You can help by
choosing one of the links below to provide feedback about this product.
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